The best US state for landscape photography is the place that you like. I'll suggest that all 50 have much to offer if you keep your eyes open- even though there are some few I've never visited. David Plowden loves the midwest and has done great work there. Of course California has been a mecca since the days of Muybridge and Watkins. Paul Strand and Paul Caponigro (among many others) did great work in New England. I've spent most of my life in the beautiful, if unspectacular, landscape of western New York State- and realized after I'd moved away that I'd barely scratched the surface. The late John Pfahl did a wonderful series on the Susquehanna river valley in Pennsylvania. There are countless other examples...Corran's comments are spot-on. There's a lifetime of work in front of you wherever you are, if you can see it. So go where the landscape inspires you, regardless of national parks, tax rates, camera clubs, or anything else. You'll find a way!